I am a volunteer fireman and storm spotter. Our busiest time in Central Nebraska is in the spring and early summer mostly in the early evening hours. The way it works is the spotters monitor suspicious cloud formations from strategic locations and radio in observed tornadic activity into the local communications center who in turn activate the sirens. When spotters are not out, as is sometimes the case this whole process is delayed. The communication center is in contact with the national weather service who in turn relay to the news media. Does that sound like a lot of middle men? Well it is. Twelve minutes after the above mentioned incident The tornado sirens were activated, a little bit to late from my perspective. Tornadoes strike fast and sometimes it is raining and or hailing so hard that nothing can be observed anyway and you just have to go by the weather service warning and seek shelter.
The following comes from FEMA's web site http://www.fema.gov/hazard/tornado/index.shtm
Tornadoes are nature’s most violent storms. Spawned from powerful thunderstorms, tornadoes can cause fatalities and devastate a neighborhood in seconds. A tornado appears as a rotating, funnel-shaped cloud that extends from a thunderstorm to the ground with whirling winds that can reach 300 miles per hour. Damage paths can be in excess of one mile wide and 50 miles long. Every state is at some risk from this hazard.
Some tornadoes are clearly visible, while rain or nearby low-hanging clouds obscure others. Occasionally, tornadoes develop so rapidly that little, if any, advance warning is possible.
Before a tornado hits, the wind may die down and the air may become very still. A cloud of debris can mark the location of a tornado even if a funnel is not visible. Tornadoes generally occur near the trailing edge of a thunderstorm. It is not uncommon to see clear, sunlit skies behind a tornado.
The following are facts about tornadoes:
- They may strike quickly, with little or no warning.
- They may appear nearly transparent until dust and debris are picked up or a cloud forms in the funnel.
- The average tornado moves Southwest to Northeast, but tornadoes have been known to move in any direction.
- The average forward speed of a tornado is 30 MPH, but may vary from stationary to 70 MPH.
- Tornadoes can accompany tropical storms and hurricanes as they move onto land.
- Waterspouts are tornadoes that form over water.
- Tornadoes are most frequently reported east of the
Rocky Mountainsduring spring and summer months.
- Peak tornado season in the southern states is March through May; in the northern states, it is late spring through early summer.
- Tornadoes are most likely to occur between and , but can occur at any time.